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1.
Triacylglycerol lipase activities in tissues of Antarctic fishes 总被引:2,自引:0,他引:2
. The activity of the lipolytic enzyme, triacylglycerol lipase (TAG lipase; E.C. 3.1.1.3) was measured in heart ventricle, liver, oxidative skeletal muscle, and adipose tissue of four species of Antarctic fishes (Chaenocephalus aceratus, Notothenia coriiceps, Trematomus newnesi, Gobionotothen gibberifrons). Estimates of weight-specific activities at 0°C in tissues of the Antarctic fishes were broadly comparable to those reported for temperate-zone fish species assayed at their physiological temperature. Within each species, liver tissue displayed the highest weight-specific activity of TAG lipase in C. aceratus, T. newnesi, and G. gibberifrons, while adipose tissue of N. coriiceps showed the highest activity within that species. Combining these estimates with carefully measured somatic indices of the tissues, permitted assessment of the relative importance of different tissues to overall lipolytic capacity on an organismal level. On this basis, liver tissue displays the greatest capacity of TAG lipase per 100 g body weight in each of the species studied. 相似文献
2.
3.
Hulbert AJ Turner N Hinde J Else P Guderley H 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2006,176(2):93-105
Mitochondria were isolated from the liver, kidney and mixed hindlimb skeletal muscle of three vertebrate species; the laboratory
rat Rattus norvegicus, the bearded dragon lizard Pogona vitticeps, and the cane toad Bufo marinus. These vertebrate species are approximately the same body mass and have similar body temperatures. The content of cytochromes
B, C, C1, and A were measured in these isolated mitochondria by oxidised–reduced difference spectra. Adenine nucleotide translocase
(ANT) was measured by titration of mitochondrial respiration with carboxyactractyloside and the protein and phospholipid content
of isolated mitochondria were also measured. Fatty acid composition of mitochondrial phospholipids was measured. Mitochondrial
respiration was measured at 37°C under states III and IV conditions as well as during oligomycin inhibition. Species differed
in the ratios of different mitochondrial cytochromes. Muscle mitochondria differed from kidney and liver mitochondria by having
a higher ANT content relative to cytochrome content. Respiration rates were compared relative to a number of denominators
and found to be most variable when expressed relative to mitochondrial protein content and least variable when expressed relative
to mitochondrial cytochrome A and ANT content. The turnover of cytochromes was calculated and found to vary between 1 and
94 electrons s−1. The molecular activity of mitochondrial cytochromes was found to be significantly positively correlated with the relative
polyunsaturation of mitochondrial membrane lipids. 相似文献
4.
Adaptation and acclimation of growth and photosynthesis of five Antarctic red algae to low temperatures 总被引:2,自引:0,他引:2
Temperature requirements for growth, photosynthesis and dark respiration were determined for five Antarctic red algal species.
After acclimation, the stenothermal species Gigartina skottsbergii and Ballia callitricha grew at 0 or up to 5 °C, respectively; the eurythermal species Kallymenia antarctica, Gymnogongrus antarcticus and Phyllophora ahnfeltioides grew up to 10 °C. The temperature optima of photosynthesis were between 10 and 15 °C in the stenothermal species and between
15 and 25 °C in the eurythermal species, irrespective of the growth temperature. This shows that the temperature optima for
photosynthesis are located well below the optima from species of other biogeographical regions, even from the Arctic. Respiratory
rates rose with increasing temperatures. In contrast to photosynthesis, no temperature optimum was evident between 0 and 25 °C.
Partial acclimation of photosynthetic capacity to growth temperature was found in two species. B. callitricha and Gymnogongrus antarcticus acclimate to 0 °C, and 5 and 0 °C, respectively. But acclimation did in no case lead to an overall shift in the temperature
optimum of photosynthesis. B. callitricha and Gymnogongrus antarcticus showed acclimation of respiration to 5 °C, and P. ahnfeltioides to 5 and 10 °C, resulting in a temperature independence of respiration when measured at growth temperature. With respect
to the acclimation potential of the species, no distinction can be made between the stenothermal versus the eurythermal group.
(Net)photosynthetic capacity:respiration (P:R) ratios showed in all species highest values at 0 °C and decreased continuously to values lower than 1.0 at 25 °C. In turn,
the low P:R ratios at higher temperatures are assumed to determine the upper temperature growth limit of the studied species. Estimated
daily carbon balance reached values between 4.1 and 30.7 mg C g−1 FW day−1 at 0 °C, 16:8 h light/dark cycle, 12–40 μmol m−2 s−1.
Received: 4 November 1999 / Accepted: 7 March 2000 相似文献
5.
Tor Myking 《Trees - Structure and Function》1997,12(2):107-112
Effects of fluctuating and constant temperatures on budburst time, and respiration in winter buds were studied in Betula pubescens Ehrh. Dormant seedlings were chilled at 0°C for 4 months and then allowed to sprout in long days (LD, 24 h) at constant temperatures
of 6, 9, 12, 15, 18 and 21°C, and at diurnally fluctuating temperatures (12/12 h, LD 24 h) with means of 9, 12, 15 and 18°C.
No difference in thermal time requirements for budburst was found between plants receiving constant and fluctuating temperatures.
The base temperature for thermal time accumulation was estimated to 1°C. Respiration in post-dormant (dormancy fully released)
excised winter buds from an adult tree increased exponentially with temperature and was 20 times as high at 30°C than at 0°C.
However, respiration in buds without scales was 30% higher at 0°C, and it was 2.7 times higher at 24°C than in intact buds.
Thus, the tight bud scales probably constrain respiration and growth and are likely to delay budburst in spring. Arrhenius
plots of the respiration data were biphasic with breaks at 13–15°C. However, this phase transition is unlikely to be associated
with chilling sensitivity since the present species is hardy and adapted to a boreal climate.
Received: 10 January 1997 / Accepted: 23 June 1997 相似文献
6.
Stichococcus, a genus of green algae, distributes in ice-free areas throughout Antarctica. To understand adaptive strategies of Stichococcus to permanently cold environments, the physiological responses to temperature of two psychrotolerants, S. bacillaris NJ-10 and S. minutus NJ-17, isolated from rock surfaces in Antarctica were compared with that of one temperate S. bacillaris FACHB753. Two Antarctic Stichococcus strains grew at temperature from 4 to 25°C, while the temperate strain could grow above 30°C but could not survive at 4°C.
The photosynthetic activity of FACHB753 at lower than 10°C was less than that of Antarctic algae. Nitrate reductase in NJ-10
and NJ-17 had its optimal temperature at 20°C, in comparison, the maximal activity of nitrate reductase in FACHB753 was found
at 25°C. When cultured at 4–15°C a large portion of unsaturated fatty acids in the two Antarctic species was detected and
the regulation of the degree of unsaturation of fatty acids by temperature was observed only above 15°C, though the content
of the major unsaturated fatty acid αC18:3 in FACHB753 decreased with the temperatures elevated from 10 to 25°C. Elevated
nitrate reductase activity and photosynthetic rates at low temperatures together with the high proportion of unsaturated fatty
acids contribute to the ability of the Antarctic Stichococcus to thrive. 相似文献
7.
Tor Myking 《Trees - Structure and Function》1998,12(4):224-229
Respiration in vegetative buds of mature Betula pendula, Alnus glutinosa and Prunus padus trees was measured monthly at 15°C from mid-October 1996 to natural outdoor budburst in April 1997. In B. pendula the effect of bud water content on respiration was also estimated (December–April) by artificial imbibition of buds for 24
h prior to measurement of respiration. For estimation of corresponding bud dormancy status, batches of twigs were forced at
identical monthly intervals at 15°C in long days (24 h), and budburst recorded. In all species dormancy was deepest when the
leaves were shed in October, and dormancy was first alleviated in P. padus followed by B. pendula and A. glutinosa. However, bud respiration capacity was not related to dormancy release as it decreased in all species from October to November
and displayed no notable increase until February in P. padus, March in B. pendula and April in A. glutinosa, after completion of dormancy release. Rather, increase in respiration coincided with growth resumption prior to budburst.
Artificial imbibition of B. pendula buds increased the water content by approximately 10% (FW) and induced a doubling of the respiration rate (December–February).
Moreover, the seasonal variation in bud water content (October–April) explained 94% of the variation in respiration in B. pendula and P. padus, and 84% in A. glutinosa. These observations suggest an important role of water content for respiration. During a cold period from mid-December to
mid-January with mean temperature of –9.7°C dormancy release was arrested in P. padus, and to some degree in A. glutinosa, whereas dormancy release progressed normally in B. pendula. This indicates species differences in lower critical temperatures for dormancy release.
Received: 30 June 1997 / Acceped: 1 October 1997 相似文献
8.
The mitochondria of intertidal invertebrates continue to function when organisms are exposed to rapid substantial shifts in
temperature. To test if mitochondrial physiology of the clam Mercenaria mercenaria is compromised under elevated temperatures, we measured mitochondrial respiration efficiency at 15°C, 18°C, and 21°C using
a novel, high-throughput, microplate respirometry methodology developed for this study. Though phosphorylating (state 3) and
resting (state 4) respiration rates were unaffected over this temperature range, respiratory control ratios (RCRs: ratio of
state 3 to state 4 respiration rates) decreased significantly above 18°C (p < 0.05). The drop in RCR was not associated with reduction of phosphorylation efficiency, suggesting that, while aerobic
scope of mitochondrial respiration is limited at elevated temperatures, mitochondria continue to efficiently produce adenosine
triphosphate. We further investigated the response of clam mitochondria to elevated temperatures by monitoring phosphorylation
of mitochondrial protein. Three proteins clearly demonstrated significant time- and temperature-specific phosphorylation patterns.
The protein-specific patterns of phosphorylation may suggest that a suite of protein kinases and phosphatases regulate mitochondrial
physiology in response to temperature. Thus, while aerobic scope of clam mitochondrial respiration is reduced at moderate
temperatures, specific protein phosphorylation responses reflect large shifts in function that are initiated within the organelle
at higher temperatures. 相似文献
9.
Oxygen demand elicited by the main cellular energy consumers was examined in isolated hepatocytes of sub-Antarctic (Lepidonotothen larseni) and high-Antarctic notothenioids (Trematomus eulepidotus, Trematomus pennellii, Trematomus lepidorhinus, Trematomus bernacchii, Artedidraco orianae) and in a zoarcid (Pachycara brachycephalum) fish with respect to the role of cellular metabolism in co-defining thermal tolerance. The relative proportions of energy
allocated to protein and RNA/DNA synthesis, ion regulation and ATP synthesis were quantified between 0°C and 15°C by analysis
of inhibitor sensitive cellular respiration. In all the investigated species, protein synthesis constituted 25–37%, RNA synthesis
24–35%, Na+/K+-ATPase 40–45% and mitochondrial ATP synthesis 57–65% of total respiration. The sub-Antarctic nototheniid L. larseni displayed lower cellular protein synthesis rates but somewhat higher active ion regulation activities than its high-Antarctic
confamilials, as is typical for more eurythermal species. Assumed thermal optima were mirrored in minimized overall cellular
energy demand. In the sub-Antarctic L. larseni and P. brachycephalum, minima of oxygen consumption were located between 3°C and 6°C, indicating elevated energy turnover below and above these
temperatures. In contrast, the high-Antarctic species displayed progressively rising respiration rates during warming with
a cellular energetic minimum at 0°C. The sub-Antarctic nototheniid and the zoarcid showed signs of cold-eurythermy and appear
to live close to their lower limit of thermal tolerance, while high-Antarctic notothenioids show high degrees of energetic
efficiency at 0°C. All cellular preparations maintained energy budgets over a wide thermal range, supporting the recent concept
that thermal limits are set by oxygen and associated energy limitations at the whole organism level. 相似文献
10.
Thermal sensitivity of mitochondrial function in the Antarctic Notothenioid Lepidonotothen nudifrons 总被引:4,自引:0,他引:4
I. Hardewig H. O. Pörtner L. S. Peck 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(8):597-604
The thermal sensitivity of mitochondrial function was investigated in the stenothermal Antarctic fish Lepidonotothen nudifrons. State 3 respiration increases with increasing temperature between 0 °C and 18 °C with a Q
10 of 2.43–2.63. State 4 respiration in the presence of oligomycin, an inhibitor of mitochondrial ATP synthase, quantifies the
leakage of protons through the inner mitochondrial membrane, which causes oxygen consumption without concomitant ATP production.
This parameter shows an unusually high Q
10 of 4.21 ± 0.42 (0–18 °C), which indicates that proton leakage does not depend merely on ion diffusion but is an enzyme-catalysed
process. The differential thermal sensitivity of oxidative phosphorylation (=state 3) and proton leakage (=state 4 in the
presence of oligomycin) leads to progressive uncoupling of the mitochondria and decreased efficiency of oxidative phosphorylation
under in vivo conditions if the body temperature of L. nudifrons increases.
Accepted: 2 September 1999 相似文献
11.
A total of nine Antarctic fish species belonging to five families were examined for their endohelminth parasite fauna. The
fishes Parachaenichthys charcoti (Bathydraconidae), Chaenocephalus aceratus (Channichtyidae), Paradiplospinus gracilis (Gempylidae), Muraenolepis microps (Muraenolepididae), Gobionotothen gibberifrons, Lepidonotothen larseni, L. nudifrons, L. squamifrons, and Trematomus eulepidopus (Nototheniidae) were caught between 80 and 608 m trawling depth off the Antarctic Peninsula (Elephant Island, King George
Island) in 1996. Nineteen different parasites species comprising five Digenea, two Cestoda, four Nematoda, and eight Acanthocephala
were found. Pseudophyllidean cestodes, the nematodes Contracaecum radiatum and C. osculatum as well as the acanthocephalan Corynosoma bullosum were the most common, infesting eight of the fish species studied with prevalences reaching 100%. Pseudoterranova decipiens
s.l. was the only parasite that was isolated from all studied fish species; however, at a lower intensity. The observed parasite
host specificity was low, and the species richness in a single fish ranged from one to eleven in a C. aceratus. This icefish and the moray cod M. microps were the most heavily infested fish, harbouring many adult and larval parasitic stages. The benthodemersal P. gracilis had only two larval parasite species, while the nototheniids had very similar parasite communities, harbouring a total of
8–14 species. Larval mammalian parasites were found to utilize fish, especially the nototheniids and channichthyids, as a
common transmission route into their final hosts. The fish parasites parallel explored different benthic host systems to reach
the most suitable host. In contrast to the coast and continental shelf, the meso/bathypelagiac zone appears to be species
poor and is inhabited by few larval forms. The fish parasite fauna off the South Shetland Islands can be characterized by
generalistic parasites that distribute within Antarctic waters according to the feeding ecology and depth range of their teleost
hosts, not only horizontally but also extending vertically into the deep sea. 相似文献
12.
Many Antarctic notothenioid species endemic to the Seasonal Pack-ice Zone have converged on adult blood serum freezing points
that are several tenths of a degree above the freezing point of seawater. While these fishes share high adult serum freezing
points, the development of their freeze avoidance during ontogeny has not been studied. We investigated this in wild caught
juveniles of one such species, Chaenocephalus aceratus (family Channichthyidae), using blood serum antifreeze activity as a proxy for their freeze avoidance. Juvenile serum antifreeze
activity was significantly below that of adults through the oldest year 2+ specimens collected. This increased at an estimated
rate of 0.368 × 10−3 ± 0.405 × 10−4°C day−1 which, if sustained, would leave C. aceratus below their adult serum antifreeze activity levels of 0.57 ± 0.08°C until 4.2 years after hatching. Underlying the 2.7-fold
increase in their serum antifreeze activity from late year 0+ juveniles to adults was an even greater 10.4-fold increase in
the concentration of their serum antifreeze glycopeptides, which increased proportionally across all of their serum AFGP size
isoforms. With insufficient antifreeze activity to avoid freezing in the ice-laden surface waters, both adult and juvenile
C. aceratus are most likely restricted to the year round ice-free waters where a metastable supercooled state can be maintained. 相似文献
13.
Weathers WW Gerhart KL Hodum PJ 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2000,170(8):561-572
We measured resting metabolic rates at air temperatures between ca. −5 and 30 °C in snow petrels (Pagodroma nivea), cape petrels (Daption capense), Antarctic petrels (Thalassoica antarctica), and Antarctic fulmars (Fulmarus glacialoides). We measured seven age classes for each species: adults, and nestlings that were 3, 8, 15, 28, 35, and 42 days old. Basal
metabolic rate (BMR) and thermal conductance (C) of adults averaged, respectively, 140% and 100% of values predicted allometrically
for nonpasserine birds. Minimum metabolic rates of unfasted nestlings aged 15–42 days averaged, respectively, 97% and 98%
of predicted adult BMR in Antarctic petrels and snow petrels, versus 119% and 126% of predicted in Antarctic fulmars and cape
petrels. Nestlings of the southerly breeding snow petrel and Antarctic petrel were relatively well insulated compared with
nestlings of other high-latitude seabirds. Adult lower critical temperature (Tlc) was inversely related to body mass and averaged 9 °C lower than predicted allometrically. As nestlings grew, their Tlc decreased with increasing body mass from ca. 14 to 22 °C (depending upon species) at 3 days of age, to −4 to 8 °C when nestlings
attained peak mass. Nestling Tlc subsequently increased as body mass decreased during pre-fledging weight recession. Nestling Tlc was close to mean air temperature from the end of brooding until fledging in the three surface nesting species.
Accepted: 12 July 2000 相似文献
14.
J. Harms 《Helgoland Marine Research》1987,41(1):45-67
Biomass (CHN), respiration rate and food uptake were estimated for the larval development ofElminius modestus at three temperatures (12, 18, 24°C). Mean values of dry weight, elemental composition and energy equivalents increased exponentially
with the development from nauplius II to VI. Dry weight, elemental composition and energy content exhibited the highest values
at 18°C. Respiration rates increased with the larval stages expressed by a power function, but increased logarithmically with
the dry weight of the larvae. The cypris larvae showed a reduced respiration rate compared with nauplius VI. The ingestion
rate was measured at a concentration of 100 cells ofSkeletonema costatum μl−1. At 12 and 18°C ingestion rates increased exponentially and at 24°C by a logarithmic function. The fittings were used to
estimate the energy budget ofE. modestus during larval development. The energy content of the larvae increased during the development from nauplius II to VI by a
factor of 21 at 12°C, 25 at 24°C and 31 at 18°C. The estimated energy content of the freshly metamorphosed barnacle is 100
mJ (12°C), 130 mJ (24°C) and 150 mJ (18°C). The assimilation- (A/I) and gross growth efficiencies (K1) increased strongly during the development from nauplius II to VI (A/I: 6–14% in nauplius II to 50–90% in nauplius VI; K1: 4% in nauplius II to 75% in nauplius VI). The net growth efficiency (K2) showed a relatively constant level ranging between 57 and 83%. 相似文献
15.
Lubomír Adamec 《Biologia》2008,63(4):515-520
Basic respiration characteristics were measured in turions of six aquatic plant species differing greatly in their ecological
and overwintering characteristics both before and after overwintering, i.e., in dormant and non-dormant state: non-carnivorous
Hydrocharis morsus-ranae and Caldesia parnassifolia and carnivorous Aldrovanda vesiculosa, Utricularia australis, U. ochroleuca, and U. bremii, and in non-dormant winter apices of three Australian (sub)tropical populations of Aldrovanda and of two temperate North American Utricularia species, U. purpurea and U. radiata. Respiration rate of autumnal (dormant) turions at 20°C ranged from 0.36 to 1.3 μmol O2 kg−1 (FM) s−1 and, except for U. bremii, increased by 11–114% after overwintering. However, this increase was statistically significant only in two species. Respiration
Q10 in dormant turions ranged within 1.8–2.6 and within 2.3–3.4 in spring (non-dormant) turions. Turions of aquatic plants behave
as typical storage, overwintering organs with low respiration rates. No relationship was found between respiration rate of
turions and overwintering strategy. In spite of their low respiration rates, turions can usually survive only from one season
to another, due to their limited reserves of respiratory substrates for long periods. Contrary to true turions, respiration
rates in non-dormant winter apices both in Australian Aldrovanda populations and temperate U. radiata and U. purpurea, in sprouting turions, and growing shoot apices of Aldrovanda were high and ranged from 2.1 to 3.1 μmol kg−1 (FM) s−1, which is comparable to that in aquatic plant leaves or shoots. 相似文献
16.
R. B. Weinstein G. N. Somero 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(3):190-196
Effects of temperature on O2 consumption by mitochondria of the Antarctic fish Trematomus bernacchii were compared with effects obtained with mitochondria from tropical (Sarotheridon mossambica) and temperate zone fishes (Sebastes carnatus and Sebastes mystinus). Arrhenius plots of O2 consumption versus temperature exhibited slope discontinuities (“breaks”) at temperatures (Arrhenius break temperatures:
ABTs) reflective of the species' adaptation temperatures. The ABT for mitochondria of T. bernacchii is the lowest reported for any animal and is ∼12 °C below the value predicted by a regression equation based on ABT data
for several invertebrates and fishes. The temperature at which the acceptor control ratio (ACR), an index of efficiency of
coupling of electron transport to synthesis of ATP, began to decrease with rising temperature also reflected adaptation temperature.
The decrease in ACR with rising temperature began at ∼18 °C for mitochondria of T. bernacchii, in contrast to ∼35 °C for mitochondria of Sarotheridon mossambica. Maintaining T. bernacchii at 4 °C for 2 weeks led to no changes in ABT or in the response of ACR to temperature. The thermal sensitivities of mitochondria
of T. bernacchii reflect the high level of cold adaptation and stenothermy that is characteristic of Antarctic Notothenioid fishes.
Accepted: 5 January 1998 相似文献
17.
Differing effects of thermal stress on coral fertilization and early embryogenesis in four Indo Pacific species 总被引:1,自引:0,他引:1
Coral reefs are expected to be severely impacted by rising seawater temperatures associated with climate change. The fertilization
and early embryogenesis of four reef-building coral species representing three Indo-Pacific families were examined in a series
of laboratory experiments where temperatures were increased up to 5–6°C at ambient. High levels of fertilization and normal
embryogenesis were observed for Favites abdita, Favites chinensis and Mycedium elephantotus at temperatures to 32°C (+5°C) and embryos developed normally until the 5th cell cleavage. Acropora millepora was the only species to be affected by higher temperatures, exhibiting significantly reduced fertilization and a higher frequency
of embryonic abnormalities at 32°C (+4°C), and fertilization ceased altogether at 34°C (+6°C). Early cell cleavage rates increased
with temperature up to 32°C for all species. 相似文献
18.
Antarctic fishes display slower annual growth rates than congeneric species from temperate zones. For an analysis of growth in relation to energy turnover, body composition was analysed in two benthic fish species to establish a whole animal energy budget. The Antarctic eelpout, Pachycara brachycephalum, was maintained at 0, 2, 4 and 6°C and the boreal eelpout, Zoarces viviparus at 4, 6, 12 and 18°C. At maximum food supply the weight gain was highest for P. brachycephalum at 4°C. Routine metabolic rate in acclimated Antarctic eelpouts did not differ between temperatures, whereas in Z. viviparus maximized growth benefited from a reduction of metabolic energy demands at 12°C. The lipid content of liver declined with increasing temperature in both species. The thermal window for growth is based on food conversion efficiency and the level of metabolic energy demand and is limited according to the level of aerobic scope available between pejus temperatures. 相似文献
19.
PAUL A. HORNE 《Physiological Entomology》1992,17(2):162-164
Abstract The respiration rates of Notonomus gravis (Chaudoir) and N.philippi (Newman) (Coleoptera: Carabidae) were measured at temperatures between 10°C and 45°C. Mature males of both species had higher respiration rates than mature females. There was no difference between the rates of teneral male and female beetles at 30°C. The difference in respiration rates between the sexes is attributed to the maternal behaviour, and decreased surface activity, of mature females. 相似文献
20.
In coastal waters, Antarctic rhodophytes are exposed to harsh environmental conditions throughout the year, like low water
temperatures ranging from −1.8°C to 2°C and high light during the summer season. Photosynthetic performance under these conditions
may be affected by slowed down enzymatic reactions and the increased generation of reactive oxygen species. The consequence
might be a chronic photoinhibition of photosynthetic primary reactions related to increased fragmentation of the D1 reaction
centre protein in photosystem II. It is hypothesized that changes in lipid composition of biomembranes may represent an adaptive
trait to maintain D1 turnover in response to temperature variation. The interactive effects of high light and low temperature
were studied on an endemic Antarctic red alga, Palmaria decipiens, sampled from two shore levels, intertidal and subtidal, and exposed to mesocosm experiments using two levels of natural
solar radiation and two different temperature regimes (2–5°C and 5–10°C). During the experimental period of 23 days, maximum
quantum yield of photosynthesis decreased in all treatments, with the intertidal specimens exposed at 5–10°C being most affected.
On the pigment level, a decreasing ratio of phycobiliproteins to chlorophyll a was found in all treatments. A pronounced decrease
in D1 protein concentration occurred in subtidal specimens exposed at 2–5°C. Marked changes in lipid composition, i.e. the
ratio of saturated to unsaturated fatty acids, indicated an effective response of specimens to temperature change. Results
provide new insights into mechanisms of stress adaptation in this key species of shallow Antarctic benthic communities. 相似文献